1. Field of the Invention
The present invention relates to room temperature (RT) curing adhesive compositions which produce bonds having high strength. More particularly, the present invention relates to RT curing adhesive compositions which fixture rapidly and have excellent high temperature properties, including hot strength and heat aging strength.
2. Brief Description of Related Technology
Great Britain Patent Document No. 2,121,811A, and German Patent Document No. 3,320,918, which appears to be a German counterpart thereof, describe a two-component acrylate adhesive. The first component is reported to have urethane/acrylate block resin, hydroxyethyl methacrylate, cumene hydroperoxide, 1-acetyl-2-phenyl hydrazine, benzene sulfimide, acrylic acid and a chelator. The second component is reported to have urethane/acrylate block resin, hydroxyethyl methacrylate, copper octoate and a chelator. The two components are mixed in a ratio by volume of 1:1. Transition metal accelerators are preferably a salt or complex of copper, nickel, cobalt or iron.
U.S. Pat. No. Re 35,058 describes an aerobically curable adhesive composition, which includes the product of combining a) a polyurethane (meth)acrylate, a (meth)acrylate comonomer other than a polyurethane (meth)acrylate, a free radical initiator and a transition metal-free accelerator and b) a second polyurethane (meth)acrylate, an additional (meth)acrylate comonomer, a drier, such as, a soluble Co, Fe, Zrm, Mn, Ce, Pb, Zn, Ca, Ba, or Y salt of an organic acid, and optionally, a copper, vanadium and nickel accelerator, subject to the proviso that if only one soluble metal salt of an organic acid is utilized in the drier, the transition metal accelerator is also utilized. Within 30 days of combining components a) and b), a surface of the adhesive composition in contact with air is no longer tacky.
U.S. Pat. No. 2,895,950 describes formulations employing hydroperoxide catalysts. Acceleration of the cure of anaerobic formulations with sulfimides, including saccharin (benzoic sulfimide), has been disclosed in U.S. Pat. No. 3,046,262.
U.S. Pat. Nos. 4,180,640 and 4,287,330 describe acyl hydrazine compounds as anaerobic accelerators preferably in combination with an acid having a pKa of about 12 or less.
Notwithstanding the state of technology, fast RT anaerobic curing composition which when cured exhibits excellent high temperature properties such as hot strength and heat aging strength have not been disclosed. There is a need for a composition which provides such physical properties.